The present invention is concerned with a mechanism for opening or closing a shut-off valve and, more particularly, with a closing mechanism for a shut-off valve capable of closing the inlet to a hot water system upon detection of leakage from the system.
Domestic hot water systems generally consist of a tank large enough to contain sufficient hot water for the needs of the user and having a heating element in its base, the tank also including an inlet from a mains water supply adjacent its base and an outlet for hot water. When hot water is drawn off through the outlet it is continuously replaced with cold water from the mains through the inlet so as to maintain the water level in the tank. It will be appreciated that if the tank springs a leak the water leaking from the tank will be continuously replaced, so the leak will continue until the flow of water through the inlet is stopped. Usually this can only be achieved by turning the domestic water supply off at its connection to the mains. This system is adequate where the leak is recognised quickly or where leakage from the hot water system can cause little or no damage.
However, there is an increasing trend towards higher density living and many people live in flats or town houses. In this type of dwelling there is either no yard or a very small yard, so hot water systems are frequently located within the dwelling, typically in a cupboard in the bathroom, laundry or a hallway. Such dwellings may also be multi-storey. Thus, if a leak occurs which is not noticed quickly by the resident, for example because the resident is not present in dwelling, the potential for damage within the resident""s dwelling and, in multi-storey complexes, the dwellings below is considerable. Very large volumes of water can leak from a hot water system in a relatively short time where a leak remains undetected and this can cause extensive damage to floor coverings and furnishings and, in multi-storey dwellings, to wiring in the ceiling of dwellings below the one in which the leak occurs. Similarly, in multi-storey office complexes damage to wiring for computers and the like in offices below the water storage tank can occur. Undoubtedly, similar situations can also occur in different contexts. Accordingly, it would be desirable to have a shut-off valve which can be actuated in response to external stimulus such as, for example, leakage of water from a domestic hot water system.
According to a first aspect of the present invention, there is provided a mechanism for opening or closing a valve through which a liquid can flow when open, the closing mechanism having valve actuation means for moving said valve from a first position to a second position under the urging of the urging means, trigger means which, when released, trigger operation of said valve actuation means, said trigger means including retainer means which ordinarily hold said shut-off valve in said first position against the force applied by said urging means, and sensor means arranged so as to be displaced by a rise in the level of the liquid when it is suitably contained, whereby displacement of said sensor means provides a stimulus which is transmitted through a mechanical interaction to said trigger means so as to release said trigger means.
Preferably the detector for sensing the level of the liquid, for example water, is a float disposed in a vessel, the float having a sufficiently low density to float upon the surface of said liquid when it enters the vessel. In this arrangement the detector for sensing the level of liquid, such as a float, is in operative association with the trigger means, whereby detection of a rise in the level of the liquid, such as by lifting of the float, releases float, releases said trigger means.
The connection between the float and the trigger means may be by a mechanical connection, and typically is a lever or a plurality of pivotally connected levers, but can also be due to a mechanical interaction such as abutment of an element connected to the sensor means and an element connected to the trigger means.
In a preferred embodiment of the invention, the valve is a shut-off valve in the inlet to a domestic hot water system, which is itself positioned inside a vessel adapted to contain a small volume of overflow water. It will be appreciated that in this application said first position has the valve open and said second position has the valve closed. In this embodiment of the invention, a float is positioned within the vessel and the float is connected to the trigger means by a series of levers. Accordingly, when water enters the vessel the float will float upon its surface and rise towards the top of the vessel, ultimately transferring a signal to the trigger means through the levers so as to release said trigger means.
The float may also be mounted in a float chamber adapted to receive any overflow water. Alternatively, the float may be located in a space between the inner wall and outer casing of the hot water system.
Typically said trigger means is an arrangement in which a pivotal motion is induced in a trigger actuating pivoting lever by the sensor means in order to release the trigger means. Preferably, the trigger actuating pivoting lever includes a portion responsive to the sensor means and a hooked projection constituting retainer means which engages a trigger pin. Typically said first portion engages or forms one end of a lever which connects the sensor means to the trigger means. The end of the lever distal to the cam is caused to move when a rise in the level of liquid is detected, thereby inducing a pivotal motion in the trigger actuating pivoting lever. The resultant pivotal motion releases the engagement of said second portion and of the trigger pin.
Preferably, said trigger means also includes displacement means for displacing the trigger pin once released. Advantageously, said displacement means comprises a trigger spring adapted to act on the trigger pin and actively displace it so as to trigger operation of said valve actuation means.
Typically the trigger pin is slidably mounted in a housing for part of its length. The trigger pin has a collar at one end which rests on said housing in the locked configuration but is acted upon by the trigger spring once the second portion of the cam disengages the trigger pin The trigger pin is in operative association with the valve actuation means at its other end, which also protrudes from the housing. This end of the trigger pin also includes means for engaging said second portion of the trigger actuating pivoting lever, typically a pin which, in the locked configuration, rests in a hooked end of said second portion of the trigger actuating pivoting lever.
In an alternative embodiment of the invention, said retainer means comprises a mechanical catch which, when released, triggers operation of said valve actuation means. Typically the mechanical catch is formed on a lever having the float attached to its other end or to the end of a connected lever. In one form of the invention the lever is adapted for pivotal motion hence, in operation, lifting of the float causes the lever to pivot and lifts the catch out of catch receiving means associated with said valve actuation means. In an alternative arrangement the catch is pushed into and out of engagement with said valve actuation means through a physical interaction between one of the group of connected levers to which the float is attached and the catch. In particular, the catch is formed on a lever whose motion is not determined by transmission of motion through the group of levers to which the float is attached, but which may come into abutment with one of said levers when they move in response to the float rising. The motion in the lever on which the catch is formed which is induced by said abutment brings the catch out of engagement with the valve actuation means so as to allow the valve to move from the open position to the closed position.
Typically, said valve actuation means has a valve rotating means such as a rotor connected to a spindle in operative association with the shut-off valve, which is a ball-type valve, said urging means being adapted to induce a rotary motion in the valve rotating means and locking means in operative association with the trigger means for preventing the induction of rotary motion in the valve rotating means until the trigger means is released.
In one embodiment of the invention, said urging means comprises a torsion spring adapted to act on a rotor connected to a spindle. In this case the locking means comprises a locking cap which extends over and around the rotor and holds the torsion spring in compressed configuration.
Interaction with the trigger pin is achieved by way of an extension from the locking cap which includes an orifice in which one end of the trigger pin is received. In this arrangement displacement of the trigger pin allows the extension of the locking cap to move also, whereas it is prevented from moving while the trigger pin cannot move, and so the locking cap is released. The release of the locking cap releases the pressure maintaining the torsion spring in the compressed configuration and a rotary motion is spontaneously induced in the rotor and transmitted to the spindle, with the result that the shut-off valve is actuated.
In an alternative embodiment of the invention, said urging means comprises at least one compression spring adapted to apply a rotational force to a rotor connected to a spindle. Preferably, the arrangement comprises two offset compression springs, each of which acts on a roller-type pin which in turn acts on said rotor. In this arrangement each of the pins has an orifice formed on its top surface in which one end of the trigger pin can be received. When the trigger pin is received in the orifice in one of the pins it is a sufficiently tight fit to prevent rotation of the pin under the urging of the compression spring acting thereon, but once the locking pin is removed the compression springs are able to decompress which induces rotation in the pins and in turn induces a rotary motion in said rotor.
In still another embodiment of the invention, said urging means comprises a compression spring adapted to act on a rotor connected to a spindle, wherein said rotor is constrained so as to be able only to move in a rotary motion. In this case the housing in which the compression spring and rotor are located comprises inner and outer sleeves, and a compression spring is located between the inner and outer sleeves but is held in the compressed configuration when the apparatus is in locked configuration. The rotor has a groove formed therein which receives pins formed on the inner sleeve, and is configured so that only a rotary motion can be induced in the rotor. The outer sleeve includes a nib which engages an arm extending from the trigger pin and this arm holds the outer sleeve close to the inner sleeve against the urging of the compression spring positioned therebetween. When the trigger pin is released, the compression spring urges the outer sleeve away from the inner sleeve and so induces a rotary motion in the rotor which is transmitted through the rotor to the spindle.
In the embodiment of the invention wherein the retainer means comprises a mechanical catch, the valve actuation means comprises a locking cap adapted for pivotal motion when mounted to the shut-off valve and defining a cavity therebetween when so mounted, and said cavity includes a spring adapted to return the locking cap to its origin. In this embodiment of the invention the locking cap is associated with the spindle attached to the ball of the shut-off valve, whereby rotation of the locking cap brings the valve from a closed to an open position where it is retained through engagement of the latch with the latch receiving means in the locking cap.
Typically, the shut-off valve is a ball valve or a butterfly valve.
According to a second aspect of the present invention there is provided a valve through which a liquid can flow when open including a valve housing provided with at least two passage ports, a passage port closure member rotatable from a first to a second position and valve actuation means for rotating said passage port closure member from said first position to said second position under the urging of urging means, trigger means which, when released, trigger operation of said valve actuation means, said trigger means including retainer means which ordinarily hold said shut-off valve in said first position against the force applied by said urging means, and sensor means arranged so as to be displaced by a rise in the level of the liquid when it is suitably contained, whereby displacement of said sensor means provides a stimulus which is transmitted through a mechanical interaction to said trigger means so as to release said trigger means.
Typically the closure member is a ball of the type used in ball valves or a flap of the type used in butterfly valves.
According to a third aspect of the present invention there is provided a hot water system suitable for domestic use including a hot water tank associated with a vessel for collecting overflow water, a mains inlet to said hot water tank from a mains supply and an outlet for hot water, said inlet including a shut-off valve having a valve housing provided with at least two passage ports, a first passage port serving as an inlet to said shut-off valve from said mains inlet and a second passage port serving as an outlet from said shut-off valve to said mains inlet, a passage port closure member rotatable from an open position in which flow through said mains inlet is unimpeded to a closed position in which flow through said mains inlet is prevented, valve actuation means for rotating said passage port closure member from an open to a closed position under the urging of urging means, trigger means which, when released, trigger operation of said valve actuation means, said trigger means including retainer means which ordinarily hold said shut-off valve in said open position against the force applied by said urging means, and sensor means arranged so as to be displaced by a rise in the level of water when it is suitably contained, whereby displacement of said sensor means provides a stimulus which is transmitted through a mechanical interaction to said trigger means so as to release said trigger means.
Typically the hot water tank is positioned within the vessel. Alternatively, a small overflow tank or chamber may be in fluid flow connection with the vessel, and the float is positioned within this, hence it is referred to as a float chamber. The float chamber may be formed as an extension of the outer wall of the hot water tank.